在C#中清除指针 [英] Clearing pointers in C#

问题描述

我的其中一个函数中有一个不安全的代码块，并且有人告诉我垃圾收集器无法清除它.我想知道如何清除那些指针.这是我的源代码.

Hi,

I have a block of unsafe code in one of my functions, and I''ve been told that the garbage collector doesn''t clean that up. I was wondering how I can clear those pointer. Here is my source code.

unsafe
          {
              byte* pointer;
              char[] devicePath = DetailData.DevicePath.ToCharArray();
              Debug.WriteLine(devicePath[0]);
              pointer = &ContextP.szDevLink;
              Debug.WriteLine((int)pointer);
              for (byte loop = 0; loop <= DetailData.DevicePath.Length - 1; loop++)
              {
                  *pointer = (byte)devicePath[loop];
                  pointer++;
              }
              pointer = null;
          }

这是szDevLink的结构.

Here is the structure that cointains szDevLink.

[StructLayout(LayoutKind.Explicit, CharSet = CharSet.Auto)]
      public struct DFUThreadContextP
      {
          [FieldOffset(0)]
          public Guid DFUGUID;
          [FieldOffset(16)]
          public Guid APPGUID;
          [FieldOffset(32)]
          public UInt32 Operation;
          [FieldOffset(36)]
          public byte bDontSendFFTransfersForUpgrade;
          [FieldOffset(40)]
          public IntPtr hImage;
          [FieldOffset(44)]
          public byte szDevLink;
          [FieldOffset(304)]
          public UInt32 dwTag;
          [FieldOffset(308)]
          public byte percent;
          [FieldOffset(309)]
          public UInt16 wTransferSize;
          [FieldOffset(311)]
          public byte LastDfuStatus_bStatus;
          [FieldOffset(312)]
          public byte LastDfuStatus_bwPollTimeout;
          [FieldOffset(315)]
          public byte LastDfuStatus_bState;
          [FieldOffset(316)]
          public byte LastDfuStatus_iString;
          [FieldOffset(317)]
          public int CurrentRequest;
          [FieldOffset(321)]
          public uint CurrentNBlock;
          [FieldOffset(325)]
          public uint CurrentLenght;
          [FieldOffset(329)]
          public UInt32 CurrentAddress;
          [FieldOffset(333)]
          public uint CurrentImageElement;
          [FieldOffset(337)]
          public UInt32 ErrorCode;
          [FieldOffset(341)]
          public IntPtr hDevice;
      }

我试图以安全模式编写代码，但是如果我没有分配正确的内存并具有C ++数据类型，则正在使用的API将无法正常工作.

我认为可以清除该问题的方法是将指针设置为null，但是我不确定，我还没有在C#中看到有关此主题的可靠文档.

在此先谢谢您.

I tried to write the code in safe mode but the API I am working with wouldn''t work properly if I don''t allocate the right memory and have the C++ data types.

The way I think I can clear it is by setting the pointer to null, however I am not sure and I haven''t seen reliable documentation about this topic in C#.

Thanks in advance.

推荐答案

请参阅我对问题的评论.您有另一个问题，缺少&ContextP.szDevLink的固定可能会导致一些令人讨厌的问题，这些问题很难调试.这样做:

Please see my comment to the question. You have a different problem, lack of pinning of &ContextP.szDevLink which may create some nasty problems which are hard to debug. Do it this way:

unsafe
            {
                //byte* pointer;
                char[] devicePath = DetailData.DevicePath.ToCharArray();
                Debug.WriteLine(devicePath[0]);
                fixed (byte* pointer = &ContextP.szDevLink) {
                    //pointer = &ContextP.szDevLink;
                    Debug.WriteLine((int)pointer);
                    for (byte loop = 0; loop <= DetailData.DevicePath.Length - 1; loop++)
                    {
                        *pointer = (byte)devicePath[loop];
                        pointer++;
                    }
                    //pointer = null; //makes no sense at all
                }
            }

请参阅:
http://msdn.microsoft.com/en-us/library/f58wzh21％28v = vs.100％29.aspx [ ^ ].

—SA

Please see:
http://msdn.microsoft.com/en-us/library/f58wzh21%28v=vs.100%29.aspx[^].

—SA

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